1. Field of Invention
The present invention relates to a method of establishing a color model for a digital image, in particular, to a method of establishing a skin color model for a digital image.
2. Related Art
For the current skin color detection, a great many images are collected in advance. After the skin colors of different races are collected, a skin color model is established by using a mixture of Gaussian probability distribution function (PDF). Skin color pixels in the image are then detected with the model.
During the detection performed by using the skin color model established in the above manner, a color space conversion or a nonlinear conversion is additionally required, such that the computing cost is relatively high and the process is complicated. Besides, as an overlapping area of the skin color and the non-skin color is quite large, misjudgment may easily occur, and the misjudged parts generally do not utilize the subsequent image processing.
In order to solve the above problems, U.S. Pat. No. 7,218,759, entitled “Face detection in digital images”, discloses the following technical means. Firstly, corresponding color distribution models are established according to a plurality of different digital images. Next, input images shot under different light sources are input. Then, the input images are analyzed by using the color distribution models. According to the method, in addition to a large amount of memory space, processing operations are required.
In practice, a model with a high complexity requires a large amount of computation, and thus does not conform to the real-time processing. If it intends to reduce the amount of computation, it is necessary to spread and save the model data in a storage device. However, the spread data is quite large, and the required storage space is also very huge.